1. Field of the Invention
The present invention relates to a light source apparatus and a projector apparatus with an optical system having reduced color irregularity.
2. Description of the Related Art
A projector apparatus is an apparatus that irradiates a reflective display device such as digital micromirror device or a transmissive display device such as liquid crystal shutter array panel with light emitted from a light source, and projects images generated by the display device onto a screen through a projection lens.
Most projectors have used a high-intensity discharge lamp as their light source. However, in recent years, many projector apparatuses have been developed in which a light emitting diode, laser diode, organic electroluminescence element or the like is used as their light source, and light emitted from the light source is converted to fluorescence of a different color by a fluorescent substance. For example, JP 2007-218956A discloses in FIG. 14 a technique to generate yellow fluorescence by irradiating a spinning color wheel with blue excitation light. This color wheel is a circular glass plate on which a fluorescent substance is partly applied. The yellow fluorescence is generated while the fluorescent substance of the color wheel is irradiated with the excitation light emitted from a blue light emitting diode. In contrast, the blue excitation light passes through the color wheel while a transparent segment of the color wheel is irradiated with the excitation light. The yellow fluorescence emitted from the fluorescent substance of the color wheel and the blue excitation light having passed through the transparent segment of the color wheel both pass through the same optical path to enter a DMD. JP 2007-218956A discloses a technique for combining the optical path of the yellow fluorescence and blue excitation light, an optical path of green light emitted from a green light emitting diode and an optical path of red light emitted from a red light emitting diode.
However, in the technique of the above-mentioned patent literature (JP 2007-218956A), there is a difference in optical path length among the optical path of the blue excitation light from the blue light emitting diode to the DMD, the optical path of the yellow fluorescence from the color wheel to the DMD, the optical path of the green light from the green light emitting diode to the DMD, and the optical path of the red light from the red light emitting diode to the DMD. Therefore, the blue excitation light, yellow fluorescence, green light and red light that enter the DMD have different luminous intensity distributions (light distributions). This results in color irregularity of the mixed light of the blue excitation light, yellow fluorescence, green light and red light that enter the DMD.
It is an object of the present invention to eliminate color irregularity of projection images that are generated from excitation light and color light casted on a casting plane.